A Smart Choice for Human Cytochromes P450 Phenotyping Assays
Drug-drug interaction can significantly impact drug safety and efficacy. Prediction of this risk of drug-drug interactions is a requisite in the development of a new drug candidate and the submission of the registration dossier. In vitro identification and measurement of the contribution of the major cytochrome P450 enzymes involved in the human metabolism of a new drug candidate, also called “CYP phenotyping”, helps predict the impact of co-administered drug(s), or perpetrator(s), on the pharmacokinetics of the new chemical entity, or the victim. Up until now, these studies are carried out using three common approaches: correlation analysis, antibody or chemical inhibition, and metabolism by recombinant human enzymes. These tests have a number of disadvantages.
Models such as correlation analysis provide no direct quantitative measurement of the contribution of each CYP in the metabolism of a drug, including:
- Models such as recombinant CYP450 enzymes are not fully representative of the liver enzyme profile
- Many chemical and antibody inhibitors lack sufficient specificity to enable confidence in results
To overcome the disadvantages of the current methodologies, a patented new in vitro drug development model was developed.
Silensomes™ are validated human pooled liver microsomes (HLMs) chemically and irreversibly inactivated for one specific CYP using mechanism based inhibitors (MBI).
Each Silensomes™ is available as cryopreserved, ready-to-use HLMs chemically knocked-out for one specific CYP activity (1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, 3A4) with each showing high specificity and efficiency of their targeted CYP inhibition (>80%), and only minor impact (<20%),
The thaw and go format of Silensomes™ enables researchers to focus more on results and less on validating the level of CYP inhibitions. Silensomes™ are available now from Lonza for compound screening purposes and for regulatory validation.
Case Study: CYP3A4-Silensomes™
CYP3A4-Silensomes™ and its homologous control were incubated with different CYPspecific substrates.
- CYP3A4 mediated metabolism of testosterone, a pure CYP3A4substrate, was totally inhibited.
- More than 80% of CYP3A4-mediated metabolism of nifedipine and midazolam was inhibited. Residual metabolism of these substrates was inhibited by ketoconazole, revealing the CYP3A5 contribution.
- There was no impact on the other CYP activities tested.
|SIL200||Human hepatic CYP3A4-Silensomes™|
|SIL210||Human hepatic CYP1A2-Silensomes™|
|SIL220||Human hepatic CYP2A6-Silensomes™|
|SIL230||Human hepatic CYP2B6 Silensomes™|
|SIL240||Human hepatic CYP2D6-Silensomes™|
|SIL250||Human hepatic CYP2C8-Silensomes™|
|SIL260||Human hepatic CYP2C9-Silensomes™|
|SIL270*||Human hepatic CYP2C19-Silensomes™|
|SIL280*||Human hepatic CYP2E1-Silensomes™|
|SIL201||Human hepatic Control CYP3A4-Silensomes™|
|SIL211||Human hepatic Control CYP1A2-Silensomes™|
|SIL221||Human hepatic Control CYP2A6-Silensomes™|
|SIL231||Human hepatic Control CYP2B6 Silensomes™|
|SIL241||Human hepatic Control CYP2D6-Silensomes™|
|SIL251||Human hepatic Control CYP2C8-Silensomes™|
|SIL261||Human hepatic Control CYP2C9-Silensomes™|
|SIL271*||Human hepatic CYP2C19-Silensomes™|
|SIL281*||Human hepatic Control CYP2E1-Silensomes™|